This invention relates to a display processing technique for use in instances when a single display is used to represent multiple parameters whose values may be correlated or interrelated with one another. Most particularly, the invention is useful when simultaneously displaying a plot of position vs. time and some other parameter whose value changes with position, time, or both. As one example of the utility of the invention, an application to a numerical control device for an electric discharge machining apparatus will be disclosed herein. According to the invention as applied to such a system, upon the designation of a portion or "range" of a machining trace graphic display, i.e., a display Of the machining path along the workpiece, the designated range of the machining trace graphic display is magnified. At the same time, a graphic display of machining voltage or machining speed versus machining elapsed time corresponding to the magnified trace is displayed.
FIG. 9 is a block diagram of a conventional numerical control device for an electric discharge machining apparatus. In this drawing, 1 is a central processing unit (hereinafter referred to as a CPU) for analyzing input information, 2 is a memory for storing machining condition data and the like, 3 is a current position detecting unit for detecting the current machining position, 4 is a current position sampling unit for sampling the current position data from the position detecting unit 3 at certain intervals of time, 5 is a machining voltage measuring unit for measuring machining voltage, 6 is a machining voltage sampling unit for sampling the machining voltage data at certain intervals of time, 7 is a machining trace graphic display unit for displaying a machining trace, 8 is a machining voltage graphic display unit for displaying a plot of machining voltage versus machining time, 9 is a keyboard for accepting key operations in designating a range or frame or the like, 10 is a paper tape reader for reading machining data punched in paper tape form, and 11 is a bus connecting the CPU 1, memory 2, current position sampling unit 4, machining voltage sampling unit 6, machining trace graphic display unit 7, machining voltage graph display unit 8, keyboard 9, and paper tape reader 10 together.
The operation of the foregoing conventional device will be described. As shown in FIG. 10, in step S1, it is judged whether machining is taking place or not. If no machining is taking place, step S1 is simply repeated. On the other hand, if machining is taking place, in step S2, machining voltage data 12 sampled by the machining voltage sampling unit 6 is extracted. In step S3, the data extracted in step S2 is added to a group of machining voltage data points (shown in FIG. 11) stored in the memory 2. In step S4, a machining voltage graph is presented using the machining voltage data 12 thus extracted. Then, control returns to step S1 and the foregoing processing is repeated. As a result, the group of machining voltage data points are stored in the memory 2 through sampling processing.
When presenting a magnified display using such data, as shown in FIG. 12, in step S5, upper and lower limit data are entered using the keyboard 9. The limit data control how much of the machining voltage axis and the machining elapsed time axis will be displayed. The ranges are indicated in given areas 14 and 15 on the display screen 13 as shown in FIG. 13. In step S6, the magnification factor of the machining voltage display is calculated using the upper and lower limit data for each axis entered in step S5, and fixed parameters relating to the size of the display region. In step S7, the magnification factor of the display screen is changed using the value calculated in step S6. With the foregoing, the preparations for graphic display of the machining voltage (steps S8 through S11) are complete.
In step S8, the machining voltage data points 12 stored in the memory 2 through machining voltage sampling processing are retrieved successively, beginning with the data collected at the start of machining. In step S9, it is judged whether or not each machining voltage data point 12 thus retrieved falls between the upper and lower voltage and time limits entered in step S5. If the data falls within these limits, in step S10, it is graphically displayed within the machining voltage display area 16, and control proceeds to step S11. On the other hand, if the data falls outside the user-defined limits, control proceeds directly to step S11. In Step 11, it is judged whether or not all of the machining voltage data points 12 have been subjected to the processing of steps S8 through S11. If not, the next datum 12 is subjected to such processing. If so, processing comes to an end.
With the foregoing processing operation, a machining voltage display 17 is generated and presented o the display screen 13 as shown in FIG. 13. Display of the machining trace itself will now be described. As shown in FIG. 14, in step S1, it is judged whether machining is taking place or not. If no machining is taking place, the judgment of step S1 is simply repeated. On the other hand, if machining is taking place, in step S12, current position data 17 sampled by the current position sampling unit 4 is extracted. In step S13, the data extracted in step S12 is added to a group of current position data points (shown in FIG. 15) stored in the memory 2. In step S14, the machining trace graphic display is presented using the current position data 17 so extracted. Then, control returns to step S1 to repeat the process. As a result, the group of current position data points are stored in the memory 2 through sampling processing, to be used in generating the display.
The magnification of the machining trace graphic display will now be described. As shown in FIG. 16, in step S15, input key information for designation of the range or frame 18 shown in FIG. 17 which defines the portion to be magnified is read. In step S16, the coordinates of the range or frame thus designated are calculated on the basis of the keyed-in information. In step S17, the magnification factor is calculated so as to enlarge the designated frame 18 to the size of the overall display area. In step S18, the existing magnification factor is changed to the factor calculated in step S17. With the foregoing, the preparations for the graphic display of the machining trace (performed in steps S8 through S11) are complete.
In step S8, the current position data points 17 stored in the memory 2 through the sampling processing of FIG. 14 are retrieved successively starting from the machining start point. In step S9, it is judged whether or not the coordinates of the position data point 17 currently being retrieved place it inside the frame obtained in step S16. If the point is inside the frame, in step S19, this current position data point 17 is graphically displayed on the trace display area 24, and control proceeds to step S11. On the other hand, if the point is not inside the frame, control proceeds directly to step S11. In step S11, it is judged whether or not all the current position data points 17 have been subjected to the processing of steps S8 through S11. If not, the next current position data point 17 is subjected to this processing. The flowchart process is completed when all the data points have been processed.
With the foregoing graphic display processing, the machining trace 24 is initially presented on the display unit 13 as shown in FIG. 17. Through a series of cursor operations, the portion of the machining trace which is to be magnified for further display is designated. While there are several ways of accomplishing this designation, one manner which may be used is to designate points B, C and D (reference numerals 20-22) on the trace by the use of the cursor, to thereby allow automatic determination of the frame 18 defining the portion to be magnified. Following the determination of the frame, that portion of the machining trace inside the frame 18 is displayed on the graphic display area 25 in magnified form as shown in FIG. 18.
As described above, the prior art adopts both machining graphic display processing and machining voltage display processing, but the two processes are completely independent of each other.
Although the foregoing description concerns machining voltage display processing, machining speed display processing in the prior art is similar and is also completely independent of trace display processing. Where a machining speed graphic display is to be presented, the machining voltage detecting unit 5 of FIG. 9 would be replaced with a machining speed detecting unit, and the machining voltage sampling unit 6 would be replaced with a machining speed sampling unit. The software would be essentially unchanged.
With the foregoing configuration of the conventional electric discharge machining apparatus, when the operator wishes to present on the display unit a graph of machining voltage or machining speed versus elapsed machining time, the elapsed time range must be set. In this connection, if it is desired to see the voltage pattern during the machining of a selected part of the workpiece, it is necessary for the operator to determine the time when machining of the portion of interest starts and when it ends. However, this is quite difficult to do in practice because there is no easy way of correlating the position data to the speed or voltage data. As a result, the operator cannot easily determine which portion of the shape being machined corresponds to what part of the graph of machining voltage versus elapsed machining time. Thus, the graphic data thus presented cannot be utilized effectively.